30 minutes is fine but make sure it's 30 minutes at the time and day of the week that you are having the wedding. 30 minutes at 10 am on a Tuesday might turn into an hour or more at 5 pm on the weekend, KWIM? I wouldn't go any higher than 30 minutes.

I personally would not want to drive 30 minutes for a continuation of the same event. My personal preference is no more than 20. However, if I was invited and a 30 minute drive was required, it wouldn't stop me from going. As PPs have said, just make absolutely sure that the drive won't take any longer than 30 minutes during the time you expect them to travel.